European Waterchestnut

Trapa natans L

Large green shiny leaves with small yellow flower

Photo Credit: Leslie J. Mehrhoff, University Of Connecticut, Bugwood.org

Plant Description

Annual plant that grows rooted to the river bottom with a floating rosette of rounded diamond-shaped toothed leaves. Feather like leaves along submerged stems. Distinctive nut-like seed with four curved horns, seed is green when fresh and brown when dried. Rosettes up to 30 cm in diameter, denes floating mats can grow up to 15 ft.

Plant Details

Life Forms	Aquatic
Habitats	Aquatic Floating Lakes Ponds Rivers
ODA Listing	A
Soil and Moisture Conditions	Aquatic
Suggested Actions	Report to Oregon Invasives Hotline
Mature Height	leaves at water's surface
Distribution	Has not been found in Oregon. Established in Northeast US and parts of Canada.
Control	Complete removal by manual or mechanical techniques.
Reproduction and Spread	Reproduces by seed and vegetatively. Seeds viable for up to 10 years. Small branches can break off, float away, and produce new infestations.
Introduced	It was first introduced in the US in the 1850s-1870s as an ornamental plant.
Look Alikes	Not easily confsed with other species
Impact	Forms dense surface mats that crowd out native vegetation and reduce oxygen and light levels in the water below. Can limit recreational enjoyment of Aquatic environments and has very little value for waterfowl.
More Info	https://www.cabi.org/isc/datasheet/55040 https://www.invasive.org/alien/pubs/midatlantic/trna.htm